JP5260130B2 - Ultrasonic inspection apparatus, ultrasonic inspection method, and non-destructive inspection method for nuclear power plant - Google Patents

Description

  The present invention relates to an ultrasonic inspection apparatus, an ultrasonic inspection method, and a nuclear plant nondestructive inspection method.

An inspection apparatus using ultrasonic waves has been put into practical use in, for example, medical care, non-destructive inspection in a nuclear power plant, and the like. For example, since the ultrasonic flaw detection test can detect defects inside the material relatively easily, it is used for inspection of important parts of the structural material and plays a major role. In the ultrasonic flaw detection test, for example, a piezoelectric element is used for transmitting ultrasonic waves as disclosed in Patent Document 1.
Since this piezoelectric element is relatively large, for example, about 20 mm in diameter, the apparatus is large. For this reason, it is difficult to measure a narrow part or a member having a complicated shape. Further, since the frequency band of the ultrasonic wave is limited by the natural frequency of the piezoelectric element, there is a problem that it is not suitable for applications such as image display on the surface of a member.

In order to solve these problems, for example, a laser ultrasonic method disclosed in Patent Document 2 has been proposed.
This is to irradiate a subject with laser light using an optical fiber, excite ultrasonic waves on the surface of the object to be inspected with this laser light, and detect ultrasonic waves transmitted through the subject with received laser light. Defects can be detected by sensing this change in ultrasonic waves, and depth can be identified by frequency analysis of the received ultrasonic waves.
That is, since a thin optical fiber is used for ultrasonic generation, the apparatus can be miniaturized and can cope with measurement of a narrow part or a member having a complicated shape.

Further, for example, as disclosed in Patent Document 3, an ultrasonic wave is generated using laser light, and a nondestructive inspection is performed using the ultrasonic wave.
This is because one end is closed by a metal plate and a laser beam is radiated into a cylindrical body in which gas is enclosed, causing a change due to the thermal expansion of the internal gas and the thermal stress of the metal plate. It propagates and generates ultrasonic waves.

JP 2000-28589 A JP 2005-43139 A Japanese Patent No. 2984390

By the way, the thing shown by patent document 2 has a problem that there exists a possibility of deteriorating and deform | transforming a test subject, since a test object is directly irradiated with a laser beam.
In addition, this limits the intensity of the laser beam, and there is a problem that sufficient investigation cannot be performed or the range of the subject to be examined is limited.
Furthermore, there is a problem that inspection cannot be performed in a place where laser light cannot pass, for example, in sodium which is a coolant for a fast breeder reactor.
In the device disclosed in Patent Document 3, since the laser beam is not directly irradiated onto the subject, it is solved that the subject is deteriorated or deformed. By the way, in order to perform a nondestructive inspection using ultrasonic waves, it is necessary to sufficiently increase the intensity of ultrasonic waves. However, since this point is not specifically shown in Patent Document 3, it cannot be carried out as it is. .
In addition, there is a strong demand for an ultrasonic inspection apparatus having a specific mode that can generate ultrasonic waves having optimal intensity or directivity corresponding to the type of subject and the type of inspection and can cope with the variety of inspections.

In view of the above circumstances, the present invention provides an ultrasonic inspection apparatus, an ultrasonic inspection method, and a non-destructive inspection method for a nuclear power plant that can efficiently generate ultrasonic waves with sufficient intensity and can perform a good inspection over a wide range. It is intended to provide.
In addition, an ultrasonic inspection device, an ultrasonic inspection method, and a non-destructive inspection of a nuclear power plant that can generate ultrasonic waves having an optimal intensity or directivity corresponding to the type of inspection object and inspection type, and can respond to a variety of inspections. It aims to provide a method.

The present invention employs the following means in order to solve the above problems.
An ultrasonic inspection apparatus according to the present invention includes a laser device that emits a laser beam having an adjusted output, and an ultrasonic transmission unit that has a transmission diaphragm that emits an ultrasonic wave that is irradiated with the laser beam emitted by the laser device, An ultrasonic inspection apparatus for performing an inspection by irradiating a subject with ultrasonic waves generated by the transmission diaphragm of the ultrasonic transmission unit, and adjusting a beam diameter of the laser light irradiated on the transmission diaphragm Beam diameter adjusting means is provided, and the laser device is provided with a plurality of optical fibers each emitting the laser light and having different diameters, and the beam diameter adjusting means includes any of the plurality of optical fibers. It is characterized by selecting whether to use.
Further, in the above invention, the transmitting diaphragm may be formed of titanium.
Further, in the above invention, the transmitting diaphragm may be formed of aluminum.

According to these inventions, the transmission diaphragm generates ultrasonic waves by irradiating the transmission diaphragm with the adjusted output laser light emitted from the laser apparatus, and the subject is irradiated with the ultrasonic waves. Deterioration and deformation can be prevented.
Thereby, since a high output laser beam can be handled, the intensity | strength of the ultrasonic wave to generate | occur | produce can be strengthened. For this reason, a good inspection can be performed.
Moreover, since sufficient examination can be performed even if the distance to the subject is increased, the directivity can be increased. Thereby, since the resolution can be reduced, the inspection accuracy can be improved.
Further, as a result of intensive studies, the present inventors have found that the directivity changes depending on the size of the beam diameter of the laser beam, and the intensity of the ultrasonic wave generated by the transmission diaphragm is different even with the same energy, that is, We found that the ultrasonic generation mode of the transmission diaphragm is different.
That is, if the beam diameter is reduced, the directivity is increased. In other words, high-intensity ultrasonic waves can be output over a wide range, which is effective for, for example, surface inspection in which the surface is imaged and inspected. On the other hand, when the beam diameter is increased, the directivity is lowered. In other words, since high-intensity ultrasonic waves are concentrated and output in a limited range, for example, it is effective for volume inspection for inspecting internal defects. .
Thus, by providing the beam diameter adjusting means, it is possible to cope with changes in the type of the subject, the examination location, etc. with a single ultrasonic examination apparatus. Also, for example, inspections with different personalities, such as volume inspection and surface inspection, that is, a hybrid inspection can be performed.
In addition, as a result of intensive studies , the present inventors have found that titanium and aluminum generate high-intensity ultrasonic waves and are useful as a transmission diaphragm. In addition, it is also useful for a transmission diaphragm formed of titanium or aluminum to generate high-intensity ultrasonic waves compared to other materials with respect to energy input to the transmission diaphragm by laser light. Thus, since energy efficiency is good, sufficient intensity | strength ultrasonic wave can be generated efficiently.

Moreover, in the said invention, the laser incident side of the said transmission diaphragm may be restrained by the optical member.

As a result of intensive studies, the present inventors have found that restraining the transmission diaphragm with an optical member increases the intensity of the generated ultrasonic waves. This is considered to be the following phenomenon, for example.
Since the laser incident side of the transmission diaphragm is constrained by the optical member, when the laser beam is irradiated to the transmission diaphragm and deformed, the deformation acts on the optical member. Since the reaction force from the optical member acts on the transmission diaphragm in the ultrasonic wave generation direction, the intensity of the ultrasonic wave generated by the transmission diaphragm is increased.
Further, since the optical member suppresses deterioration or damage of the transmission diaphragm due to the laser beam, the intensity of the laser beam can be increased and the intensity of the generated ultrasonic wave can be increased.
As the optical member, glass such as sapphire or quartz, ceramics such as an aluminum oxide film, or the like is used.
Further, the optical member and the transmission diaphragm may be joined or simply disposed adjacent to each other.

Further, in the above invention, the laser incident side surface of the transmitting diaphragm, jelly-like viscous material may be applied.

As a result of intensive studies, the present inventors have found that the intensity of ultrasonic waves generated is increased by applying a jelly-like viscous material to the laser incident side of the transmission diaphragm. This is considered to be the following phenomenon, for example.
Among the vibrations generated in the transmission diaphragm when the laser beam is irradiated to the transmission diaphragm, the vibration toward the laser incident side is repelled by the jelly-like viscous material. It will head in the direction of occurrence. As described above, since the vibration directed in the ultrasonic wave generation direction and the vibration returned in the opposite direction are superimposed, the intensity of the ultrasonic wave generated by the transmission diaphragm is increased.
Further, since the jelly-like viscous material is easily deformed, it can be closely attached along the surface of the transmission diaphragm. As a result, the viscous material can rebound the vibration of the transmission diaphragm over the entire surface thereof, so that energy can be efficiently transmitted in the ultrasonic wave generation direction.
The jelly-like viscous material is preferably transparent. In this way, since the transparent viscous material does not hinder the passage of the laser beam, a large amount of the laser beam is incident on the transmission diaphragm, and the intensity of the generated ultrasonic wave can be increased.
Further, the range in which the jelly-like viscous material is applied does not have to be applied to the entire surface, and at least covers the range irradiated with the laser beam. It is more preferable that the viscous material is applied so as to cover a portion where the generation of ultrasonic waves is larger than the range irradiated with the laser beam.

In addition, an ultrasonic inspection method according to the present invention includes a laser device that emits a laser beam having an adjusted output, and an ultrasonic transmission unit that includes a transmission diaphragm that emits an ultrasonic wave that is irradiated with the laser beam emitted by the laser device. And a beam diameter adjusting means for adjusting a beam diameter of the laser beam irradiated to the transmission diaphragm, wherein the laser device emits the laser beam and has a plurality of different diameters. And the beam diameter adjusting means selects which of the plurality of optical fibers to use, the beam diameter adjusting means adjusts the size of the beam diameter, and the transmission diaphragm In this case, ultrasonic waves having an intensity corresponding to the type of inspection object and the type of inspection are generated, and the inspection is performed by irradiating the subject with the ultrasonic waves.

According to the present invention, the transmission diaphragm generates an ultrasonic wave by irradiating the transmission diaphragm with the adjusted output laser light emitted from the laser device, and the ultrasonic wave is irradiated to the subject. Deterioration and deformation can be prevented.
Thereby, since a high output laser beam can be handled, the intensity | strength of the ultrasonic wave to generate | occur | produce can be strengthened. For this reason, a good inspection can be performed.
At this time, the size of the beam diameter is adjusted by the beam diameter adjusting means, an ultrasonic wave having an intensity corresponding to the type of inspection object and the inspection type is generated from the transmission diaphragm, and the subject is irradiated with this ultrasonic wave for the inspection. Therefore, for example, it is possible to perform inspections having different characteristics, that is, surface inspection for inspecting the surface by imaging and volume inspection for inspecting internal defects, that is, a hybrid inspection.

  Further, the non-destructive inspection method for a nuclear power plant according to the present invention performs non-destructive inspection of a nuclear power plant by using an ultrasonic inspection apparatus that efficiently emits ultrasonic waves of sufficient intensity by irradiating the above-described laser beam to a transmission diaphragm. It is characterized by performing.

  In this way, an ultrasonic inspection apparatus that efficiently generates ultrasonic waves of sufficient intensity by irradiating the transmission diaphragm with laser light is used, so that the laser light cannot pass through, for example, a fast breeder reactor coolant. It can be tested even in certain sodium.

According to the present invention, the transmission diaphragm generates ultrasonic waves by irradiating the transmission diaphragm with the laser light emitted from the laser device, and the ultrasonic waves are irradiated to the subject, thereby preventing deterioration and deformation of the subject. can do.
Thereby, since a high output laser beam can be handled, the intensity | strength of the ultrasonic wave to generate | occur | produce can be strengthened. For this reason, a good inspection can be performed.
Further, by providing the beam diameter adjusting means, it is possible to cope with changes in the type of the subject, the examination location, etc. with a single ultrasonic examination apparatus. For example, inspections with different personalities such as volume inspection and surface inspection, that is, a hybrid inspection can be performed.

  Hereinafter, an ultrasonic inspection apparatus 1 according to an embodiment of the present invention will be described with reference to FIGS. The ultrasonic inspection apparatus 1 performs ultrasonic flaw detection of a member in sodium that is a coolant for a fast breeder reactor, and performs volume inspection for inspecting an internal state and surface inspection for inspecting a surface state. .

FIG. 1 is a block diagram showing an overall schematic configuration of the ultrasonic inspection apparatus 1.
The ultrasonic inspection apparatus 1 includes an inspection body 3 that transmits and receives ultrasonic waves, a laser apparatus 5 that transmits laser light for ultrasonic transmission, a reception laser unit 7 that receives and transmits laser light for ultrasonic reception, A data collection device 9 for storing the transmitted / received data and instructing the operations of the laser device 5 and the reception laser unit 7 and a data processing / display device 11 for processing and displaying the transmitted / received data are provided.

  The reception laser unit 7 includes a laser oscillator 6 that oscillates laser light, an optical switch 8 that introduces and derives laser light into an optical fiber, and a laser interferometer 10 that causes transmission laser light and reception laser light to interfere with each other. ing.

FIG. 2 is a cross-sectional view showing a schematic configuration of the inspection body 3.
The inspection body 3 includes a main body 13 which is a box having a substantially rectangular parallelepiped shape, a cylindrical shape attached to a substantially central portion of one surface of the main body, a passage portion 15 through which an optical fiber is inserted, and an inside of the main body 13. An attached volume inspection ultrasonic transmission unit (ultrasonic transmission unit) 17, surface inspection ultrasonic transmission unit (ultrasonic transmission unit) 19, and a plurality of ultrasonic reception units 21 are provided.

The volume inspection ultrasonic transmission unit 17, the surface inspection ultrasonic transmission unit 19, and the ultrasonic reception unit 21 have a substantially cylindrical shape, and the axis is in a direction intersecting the surface of the main body 13 to which the passage unit 15 is attached. Thus, the main body 13 is attached to the side away from the passage portion 15.
The plurality of ultrasonic receivers 21 are installed in a matrix (for example, 10 columns × 10 rows) at substantially equal intervals.
The volume inspection ultrasonic wave transmission unit 17 and the surface inspection ultrasonic wave transmission unit 19 are respectively installed at a substantially central portion of the ultrasonic wave reception unit 21 group.

The volume inspection ultrasonic transmission unit 17 and the surface inspection ultrasonic transmission unit 19 are connected to the laser device 5 by an optical fiber 23. (See Figures 2 and 3)
Since the volume inspection ultrasonic transmission unit 17 and the surface inspection ultrasonic transmission unit 19 have substantially the same structure, the volume inspection ultrasonic transmission unit 17 will be described.
The laser device 5 includes a laser oscillator 25, a laser light path 27, and an introduction unit 29 configured to introduce laser light into the optical fiber 23, such as an optical switch.

The laser light path 27 includes a pair of mirrors 31, an ND filter 33, and a condenser lens 35.
The ND filter 33 is provided with a plurality of exchangeable filters, and adjusts the amount of laser light, that is, the output by exchanging these filters.
The condenser lens 35 is movable along the laser light path 27 so that the diameter of the laser light incident on the optical fiber 23 (the diameter of the laser light incident on the transmission diaphragm 39 described later) can be adjusted to some extent. ing.

The volume inspection ultrasonic transmitter 17 has a hollow main body 37 having a substantially cylindrical shape, a transmission diaphragm 39 attached to one end of the main body 37, a heat-resistant damper 41, and the other end of the transmission diaphragm 39. And a backup ring 43 that supports this, a ferrule 45 that is a connecting member for installing the optical fiber 23 disposed on the other end side of the backup ring 43 in a predetermined positional relationship, and a ferrule 45 that is disposed on the other end side of the ferrule 45. An eccentric hole ring 47 that holds 45 and a holding screw 49 that is screwed into a hollow portion at the other end of the main body 37 and presses a member disposed on one end side are provided.
The volume inspection ultrasonic transmission unit 17 and the surface inspection ultrasonic transmission unit 19 are installed such that the transmission diaphragm 39 faces the surface of the main body 13 facing the passage portion 15.

FIG. 4 is a cross-sectional view showing a schematic configuration of the ultrasonic receiving unit 21.
The ultrasonic receiver 21 has a substantially cylindrical shape, and an optical fiber 51 connected to the optical switch 8 is connected to one end side. A receiving diaphragm 53 is attached to the other end of the ultrasonic receiving unit 21.
The ultrasonic receiving unit 21 is installed so that the receiving diaphragm 53 faces the surface of the main body 13 facing the passage unit 15.

In addition to the condenser lens 35, the volume inspection ultrasonic transmission unit 17 and the surface inspection ultrasonic transmission unit 19 may be provided with a beam diameter adjusting means 55 as shown in FIGS. .
6 is provided with a compression spring 57 that constantly urges the ferrule 45 toward the holding screw 49 side. When the holding screw 49 is rotated and moved outward in the axial direction, the ferrule 45 is pressed by the compression spring 57 and moved outward in the axial direction like the pressing screw 49. On the contrary, when the holding screw 49 is rotated and moved to the transmission diaphragm 39 side, the ferrule 45 is moved to the transmission diaphragm 39 side against the urging force of the compression spring 57.
As a result, the distance between the tip of the ferrule 45 and the transmission diaphragm 39 changes. When this interval changes, the beam diameter of the laser light reaching the transmission diaphragm 39 changes depending on the radiation angle of the laser light emitted from the tip of the ferrule 45.
The structure for changing the distance between the emission end of the optical fiber 51 (for example, the tip of the ferrule 45) and the transmission diaphragm 39 is not limited to that shown in FIG.

The volume inspection ultrasonic transmitter 17 shown in FIG. 7 includes a plurality of optical fibers 23 having different diameters. Since the beam diameter of the laser light emitted from the optical fiber 23 differs depending on the diameter, the beam diameter of the laser light reaching the transmission diaphragm 39 can be changed by selecting the optical fiber 23 used in the laser device 5.
A convex lens 59 is attached between the ferrule 45 and the transmission diaphragm 39 so as to be movable in the axial direction in the volume inspection ultrasonic wave transmitter 17 shown in FIG. The ferrule 45 is always urged toward the holding screw 49 by a compression spring 57 as in the case of FIG.
The converging state of the laser light is changed by moving the convex lens 59 in the axial direction, and the beam diameter of the laser light reaching the transmission diaphragm 39 is changed.
In FIG. 8, the convex lens 59 is moved in the axial direction to change the beam diameter of the laser light reaching the transmission diaphragm 39. However, the present invention is not limited to this. For example, the ferrule 45 is moved in the axial direction. Alternatively, both the convex lens 59 and the ferrule 45 may be moved in the axial direction.

When the transmission diaphragm 39 is irradiated with laser light, the transmission diaphragm 39 generates ultrasonic waves.
At this time, the intensity of the generated ultrasonic wave changes as shown by the solid line in FIG. 5 corresponding to the laser beam output or the energy density of the laser beam.
Where the laser light output or the energy density of the laser light is small (low energy range), the energy of the laser light is used to raise the temperature of the transmission diaphragm 39 and the like, and the intensity of the generated ultrasonic wave is small. This part is called a thermal mode.

When the laser beam output or the energy density of the laser beam is further increased, the intensity of the generated ultrasonic wave increases rapidly. At this stage, the transmission diaphragm 39 is in a state of being eroded by the laser light, and is therefore referred to as an ablation mode.
When the laser light output or the energy density of the laser light is further increased, the erosion action on the transmission diaphragm 39 is increased and partly gasified to scatter or absorb the laser light. Therefore, the energy supplied by the laser light to the transmission diaphragm 39 The proportion will decrease.
In this case, the rate of increase in the intensity of the generated ultrasonic wave becomes small, so that the energy efficiency of the laser beam is lowered. This state is called an air breakdown mode.

  Therefore, in consideration of energy efficiency and damage to the transmission diaphragm 39, the intensity of the laser beam (laser beam output or laser beam energy density, etc.) is selected within the range of the ablation mode.

  The material, dimensions, and the like of the transmission diaphragm 39 are selected in consideration of the intensity of the laser beam from the laser device 5 and the intensity and frequency characteristics of the ultrasonic wave generated thereby. In order to improve energy efficiency, the transmission diaphragm 39 is preferably made of a material having high laser beam absorption efficiency.

Thus, since the material and characteristics of the transmission diaphragm 39 have a great influence on the performance of the ultrasonic inspection apparatus 1, a verification test was performed on them.
FIG. 9 shows a test apparatus for performing this verification test.
As a laser oscillator 25 for transmitting a YAG laser, Surelite I-10 manufactured by Contium is used. The YAG laser beam output from the laser oscillator 25 has an output of 400 mJ, a pulse interval of 10 Hz, and a pulse width of 10 ns.
A diaphragm specimen 65 is attached to an attachment member 63 provided on one surface of a water tank 61 that stores water, and ultrasonic waves generated by applying laser light from the laser oscillator 25 to the diaphragm specimen 65 are received by a piezoelectric element 67 for reception. The oscilloscope 69 measures the intensity.

As the diaphragm specimen 65, stainless steel (SUS), titanium (Ti), aluminum (Al), copper (Cu), and tin (Sn) were used. The diaphragm specimen 65 is a disk having a diameter of 25 mm and a thickness of 0.05 mm. For SUS, a 0.03 mm thick one was also used to see the effect of the thickness.
Further, the composite material 71 shown in FIG. 10 was also tested as the diaphragm specimen 65. In the composite material 71, a sapphire diaphragm (optical member) 75 made of sapphire glass having a thickness of 1 mm is bonded to one surface of a SUS diaphragm (transmitting diaphragm) 73 having a thickness of 0.03 mm, that is, a surface on which laser light is incident. It is a thing. The composite material 71 is a disc having a diameter of 30 mm.
In the composite material 71, the joint surface of the SUS diaphragm 73 is sputtered with Cr—Ni—Au. On the other hand, the joint surface of the sapphire diaphragm 75 is metallized. And the joining surface of the SUS diaphragm 73 and the sapphire diaphragm 75 is bonded and formed with Au-Sn solder. The solder layer is approximately 2 μm.

FIG. 11 shows the directivity with the beam diameter of the laser light as a parameter. In order to make the directivity state easy to understand, the signal intensity (intensity of ultrasonic waves) is normalized.
Looking at this, the directivity with a beam diameter of 0 and 5 mm is high (high intensity ultrasonic waves can be output in a wide range), and the directivity of 4 mm is low (high intensity ultrasonic waves are concentrated in a limited range. 2mm is in the middle.
That is, it has been found that the directivity increases as the beam diameter decreases.
This is presumably because the smaller the beam diameter, the higher the ablation ratio per unit area.

12 and 13 show the relationship between the signal intensity and directivity with the input energy constant in the low energy region (thermal mode) and the beam diameter of the laser light as a parameter.
Looking at this, the total signal intensity is 2 mm larger than the beam diameter of 4 mm, about 4 times in FIG. 12, and about 2.4 times in FIG.
That is, if the input energy is constant, the smaller the beam diameter, the stronger the intensity of the generated ultrasonic wave, that is, the higher the energy conversion efficiency.

14 and 15 show the relationship between signal intensity and directivity with the beam diameter of laser light as a parameter when the input energy per unit area is the same.
Looking at this, the total signal intensity is 4 mm larger than the beam diameter 2 mm, about 1.32 times in FIG. 14 and about 1.14 times in FIG.
That is, if the input energy per unit area is constant, the intensity of the generated ultrasonic wave is stronger as the beam diameter is larger, that is, the energy conversion efficiency is higher.
Thus, it has been found that the beam diameter of the laser beam has a great influence on the energy efficiency.

16 to 18 compare ultrasonic wave generation intensities depending on material types. 16 mainly shows the state of the ablation mode region (approximately 80 mJ or more), FIG. 17 shows the state of the low ablation mode region (around 50 mJ), and FIG. 18 shows the state in the thermal mode region (25 mJ or less). .
In each figure, about the composite material 71, the tendency of a measurement result is shown with the dashed-dotted line.

In the ablation mode region (FIG. 16), aluminum shows the strongest ultrasonic intensity (high energy conversion efficiency), followed by titanium and SUS. Moreover, in SUS which tested the diaphragm specimen 65 from which thickness differs, the predominance difference of the ultrasonic intensity by thickness was not found.
During the test, tin had a hole in the center of the diaphragm specimen 65. Since tin is soft, it turned out to be unsuitable for practical use.
It has been found that SUS and copper can also provide a sufficiently practical ultrasonic intensity.
The composite material 71 has an ultrasonic intensity of about 1.6 times that of aluminum and about twice or more that of SUS, which is the same material, and has demonstrated high energy conversion efficiency.
The composite material 71 was damaged by melting the surface of the sapphire glass at 300 mJ or more, and the ultrasonic strength rapidly decreased. The composite material 71 using sapphire glass is an upper limit value used around here.

In the low ablation mode region (FIG. 17), tin exhibits the strongest ultrasonic intensity, followed by aluminum and titanium.
Here, the ultrasonic intensity of the composite material 71 is substantially the same as that of tin and aluminum. However, an ultrasonic intensity of about 10 times or more is obtained for SUS which is the same material.
In the thermal mode region (FIG. 18), tin and titanium are relatively good. Further, the composite material 71 has an ultrasonic intensity that is about ten times higher than that of a single material (see FIG. 17).

It has been found that aluminum and titanium, which have good energy efficiency, are useful as materials for the transmission diaphragm 39 in the ablation mode region in which the ultrasonic intensity necessary for practical use can be obtained.
Moreover, it turned out that the composite material 71 is further useful.
This is because the laser incident side of the SUS diaphragm 73 is constrained by the sapphire diaphragm 75, and when the laser light is irradiated to the SUS diaphragm 73 and deformed, the deformation acts on the sapphire diaphragm 75. Since the reaction force from the sapphire diaphragm 75 acts on the SUS diaphragm 73 in the ultrasonic wave generation direction, the intensity of the ultrasonic wave generated by the SUS diaphragm 73 is increased.
Further, since the sapphire diaphragm 75 suppresses deterioration or damage of the SUS diaphragm 73 due to the laser light, the intensity of the generated ultrasonic wave can be increased by increasing the intensity of the laser light.

In the composite material 71, the SUS diaphragm 73 and the sapphire diaphragm 75 are joined by solder. However, the joining method is not limited to solder, and an appropriate means may be used, and the composite material 71 may be installed adjacent to each other without being joined. May be. The sapphire diaphragm 75 should just be installed so that the movement of the SUS diaphragm 73 may be restrained.
The material of the optical member constituting the composite material 71 is not limited to sapphire glass, but may be ceramic such as quartz glass or an aluminum oxide film.
Further, instead of the SUS diaphragm 73, a diaphragm such as aluminum, titanium, copper, or tin may be used.

  Further, the transmission diaphragm 39 may be coated with an oxide film of, for example, iron or aluminum on the surface. These oxide films can improve the absorption rate of the laser beam and can suppress the deterioration and damage of the transmission diaphragm 39.

A diaphragm specimen 65 having the structure shown in FIG. 19 was used for testing. The diaphragm specimen 65 is obtained by, for example, applying a viscous material (viscous material) 81 to one surface of the SUS diaphragm 73 having a thickness of 0.02 mm, that is, the surface on which laser light is incident. The SUS diaphragm 73 is a disc having a diameter of 30 mm.
As the viscous body 81, for example, SONOTECH inc. “Pyrogel GR 100” (trade name) manufactured by the company is used. This is a contact medium used as a coplant. The viscous body 81 has a transparent jelly shape mainly composed of glycerin and has a wide use temperature range of −45.6 ° C. to 427 ° C. (−50 ° F. to 800 ° F.). Further, the viscosity is as high as 4 × 10 ⁶ cps or more, and once attached, it does not flow easily.
The viscous body 81 includes a range where the laser beam is irradiated, and is applied with a thickness of about 1 mm by hand over a range exceeding the range.

On condition that the laser input energy is 10 mJ and the beam diameter of the incident laser is 2 mm, the diaphragm specimen 65 with the viscous body 81 and the diaphragm specimen 65 without the viscous body 81 (SUS of thickness 0.02 mm) A time transition of the magnitude of the ultrasonic wave generated using the diaphragm 73) was tested.
20 shows the result of the diaphragm specimen 65 with the viscous body 81, and FIG. 21 shows the result of the SUS diaphragm 73 only.
As can be seen, in the diaphragm specimen 65 with the viscous body 81, the intensity of the ultrasonic wave generated is 20 times that of the SUS diaphragm 73 alone, and a sharp ultrasonic waveform is obtained.

This is because, among the vibrations generated in the SUS diaphragm 73 when the SUS diaphragm 73 is irradiated with the laser light, the vibration toward the laser incident side is repelled by the viscous body 81, so that they are in the opposite direction to the laser incident side, that is, Then, it goes in the direction of ultrasonic generation. As described above, since the vibration directed in the ultrasonic wave generation direction and the vibration returned in the opposite direction are superimposed, the intensity of the ultrasonic wave generated by the SUS diaphragm 73 is increased.
Further, since the viscous body is easily deformed, it can be closely adhered along the surface of the SUS diaphragm 73 without any gap. Thereby, since the viscous body 81 can return the vibration of the SUS diaphragm 73 over the whole surface, energy can be efficiently sent to the ultrasonic wave generation direction.

In addition, since the transparent viscous body 81 does not hinder the passage of the laser beam, a large amount of the laser beam is incident on the SUS diaphragm 73, and the intensity of the generated ultrasonic wave can be increased.
Further, the range where the viscous body 81 is applied does not need to be applied to the entire surface, and at least covers the range irradiated with the laser beam. It is more preferable that the viscous body 81 is applied so as to cover a portion where the generation of ultrasonic waves is larger than the range irradiated with the laser light.
Here, the test results are shown for the transmission diaphragm 39 made of SUS, but this can also increase the intensity of the generated ultrasonic waves in the same manner even when the transmission diaphragm 39 is made of a material such as aluminum, titanium, copper, or tin. .

The operation of the ultrasonic inspection apparatus 1 according to the present embodiment described above will be described.
The inspection body 3 is disposed to face the structural member (subject) 77 to be inspected. When performing a volume inspection for inspecting the scratch 79 inside the structural member 77, the volume inspection ultrasonic transmitter 17 is used.
When the laser oscillator 25 oscillates the laser beam, the laser beam is incident on the introduction portion 29 through the laser beam path 27. The laser beam is converted into a form that can pass through the optical fiber 23 on the volume inspection ultrasonic wave transmission unit 17 side by the introduction unit 29. The converted laser light is irradiated from the ferrule 45 to the transmission diaphragm 39 through the optical fiber 23.

  When the transmission diaphragm 39 is irradiated with laser light, the transmission diaphragm 39 generates ultrasonic waves.

In this way, the ultrasonic waves C generated by the transmission diaphragm 39 of the volume inspection ultrasonic transmission unit 17 are irradiated toward the structural member 77.
The ultrasonic wave C is adjusted so that the frequency is mainly 2 to 5 MHz. In other words, conditions such as the material and size of the transmission diaphragm 39 and the intensity of the laser beam of the laser device 5 are set so that the frequency of the generated ultrasonic wave C is mainly 2 to 5 MHz.

The ultrasonic wave C irradiated to the structural member 77 is reflected by the structural member 77, travels toward the inspection body 3, and vibrates the reception diaphragm 53 of each ultrasonic wave reception unit 21. At this time, if there is a scratch 79 in the structural member 77, the direction of the ultrasonic wave C is changed by the scratch 79, and the phase of the vibration of the reception diaphragm 53 deviates from a predetermined state.
At this time, laser light is oscillated from the laser oscillator 6 of the reception laser unit 7 and is irradiated to the reception diaphragm 53 via the optical switch 8 and the optical fiber 51. The irradiated laser light is reflected by the receiving diaphragm 53 and returns to the laser interferometer 10 through a reverse route.

Since the receiving diaphragm 53 is oscillating, the moving distance of the laser light that comes out of the laser oscillator and returns to the laser interferometer 10 fluctuates. By causing this to interfere with the transmission laser light from the laser oscillator 6, the fluctuation state becomes clear.
This data is stored in the data collection device 9, and the data processing / display device 11 processes the stored data, and calculates and displays the presence / absence of a flaw 79, and the position of the flaw 79.

Next, when performing a surface inspection for inspecting the surface condition of the structural member 77, the surface inspection ultrasonic transmitter 19 is used.
In this case, the ultrasonic wave C generated by the transmission diaphragm 39 of the surface inspection ultrasonic transmission unit 19 is adjusted so that the frequency is mainly 10 MHz. In other words, conditions such as the material and size of the transmission diaphragm 39 and the intensity of the laser beam of the laser device 5 are set so that the frequency of the generated ultrasonic wave C is mainly 10 MHz.

As described above, when the frequency of the ultrasonic wave C is mainly 10 MHz, the ultrasonic wave C does not enter the inside of the structural member 77 and is reflected by the surface, so that the surface state is inspected. Can do.
Since the inspection operation is the same as that of the volume inspection, a duplicate description is omitted here.
As described above, the ultrasonic inspection apparatus 1 includes the volume inspection ultrasonic transmission unit 17 and the surface inspection ultrasonic transmission unit 19 having different frequencies of the generated ultrasonic wave C. Inspections with different characteristics such as inspection and surface inspection, that is, a hybrid inspection can be performed by a single unit.
Thus, by using the ultrasonic inspection apparatus 1 including the optimum transmission diaphragm 39 corresponding to the type of the structural body 77 and the inspection type, inspection accuracy, inspection efficiency, and the like can be improved.

In this way, the transmission diaphragm 39 generates the ultrasonic wave C by irradiating the transmission diaphragm 39 with the laser light emitted from the laser device 5, and the ultrasonic wave C is applied to the structural member 77. Deterioration and deformation can be prevented.
Thereby, since the high output laser beam can be handled, the intensity of the generated ultrasonic wave C can be increased. For this reason, a good inspection can be performed.
In addition, since sufficient inspection can be performed even if the distance to the structural member 77 is increased, the directivity angle can be increased. Thereby, since the resolution can be reduced, the inspection accuracy can be improved.

Further, by using the optical fibers 23 and 51 for the transmission of the laser light, the volume inspection ultrasonic transmission unit 17 and the surface inspection ultrasonic transmission unit 19 can be reduced, so that the ultrasonic inspection apparatus 1 can be miniaturized. Can do.
In addition, since the ultrasonic wave C is used for the inspection, the inspection can be performed even in a sodium that is a coolant of the fast breeder reactor, for example, where the laser beam cannot pass.

Also, as shown in FIGS. 6 to 8, the apparatus having the beam diameter adjusting means 55 for adjusting the beam diameter of the laser light adjusts the beam diameter of the laser light incident on the transmission diaphragm 39.
For example, if the beam diameter is reduced and the directivity is increased, surface inspection can be performed in which the surface is imaged and inspected. On the other hand, if the beam diameter is increased to reduce the directivity, volume inspection for inspecting internal defects can be performed.
Thus, by providing the beam diameter adjusting means 55, the volume inspection ultrasonic transmission unit 17 has the functions of the volume inspection ultrasonic transmission unit 17 and the surface inspection ultrasonic transmission unit 19. The ultrasonic inspection unit 19 for surface inspection can be omitted. That is, only the volume inspection ultrasonic transmitter 17 can perform inspections with different personalities such as volume inspection and surface inspection, that is, hybrid inspection.
In addition, for example, the directivity can be changed by deforming the transmission diaphragm 39 to be uneven in the plane.

In addition, this invention is not limited to this embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.
For example, it is not necessary to provide the volume inspection ultrasonic transmission unit 17 and the surface inspection ultrasonic transmission unit 19 at the same time, and only one of them may be provided depending on the purpose.

1 is a block diagram showing an overall schematic configuration of an ultrasonic inspection apparatus according to an embodiment of the present invention. It is sectional drawing which shows schematic structure of the test body concerning one Embodiment of this invention. It is a block diagram which shows schematic structure of the ultrasonic transmission system concerning one Embodiment of this invention. It is sectional drawing which shows schematic structure of the ultrasonic receiver concerning one Embodiment of this invention. It is a graph which shows the relationship between a laser intensity | strength and the intensity | strength of the ultrasonic wave to generate | occur | produce. It is sectional drawing which shows the other embodiment of the ultrasonic transmission part for volume inspection concerning one Embodiment of this invention. It is sectional drawing which shows the other embodiment of the ultrasonic transmission part for volume inspection concerning one Embodiment of this invention. It is sectional drawing which shows the other embodiment of the ultrasonic transmission part for volume inspection concerning one Embodiment of this invention. It is a block diagram which shows schematic structure of a test apparatus. It is sectional drawing which shows schematic structure of a composite material. It is a graph which shows the difference in directivity which made the beam diameter the parameter. It is a graph which shows the difference in the signal strength by a beam diameter on conditions with constant input energy. It is a graph which shows the difference in the signal strength by a beam diameter on conditions with constant input energy. It is a graph which shows the difference in the signal intensity by a beam diameter on condition that input energy per unit area is constant. It is a graph which shows the difference in the signal intensity by a beam diameter on condition that input energy per unit area is constant. It is a graph which shows the ultrasonic wave generation intensity by the difference in the material kind in an ablation mode area. It is a graph which shows the ultrasonic wave generation intensity | strength by the difference in the material type in a low ablation mode area | region. It is a graph which shows the ultrasonic wave generation intensity | strength by the difference in the material kind in a thermal mode area | region. It is sectional drawing which shows schematic structure of the diaphragm test body which attached the viscous body. It is a graph which shows the ultrasonic wave generation intensity | strength by the diaphragm test piece which attached the viscous body. It is a graph which shows the ultrasonic wave generation intensity | strength by the diaphragm test piece which has not attached the viscous body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic inspection apparatus 5 Laser apparatus 17 Volume inspection ultrasonic transmission part 19 Surface inspection ultrasonic transmission part 23 Optical fiber 39 Transmission diaphragm 51 Optical fiber 53 Reception diaphragm 55 Beam diameter adjustment means 71 Composite material 75 Sapphire diaphragm 77 Structural member 81 Viscous material

Claims (7)

A laser device that emits a laser beam of adjusted output, and an ultrasonic transmission unit that includes a transmission diaphragm that is irradiated with the laser light emitted by the laser device and generates an ultrasonic wave;
An ultrasonic inspection apparatus that performs an inspection by irradiating a subject with ultrasonic waves generated by the transmission diaphragm of the ultrasonic transmission unit,
A beam diameter adjusting means for adjusting a beam diameter of the laser beam applied to the transmission diaphragm;
Each of the laser devices includes a plurality of optical fibers that emit the laser light and have different diameters.
The ultrasonic inspection apparatus, wherein the beam diameter adjusting unit selects which of the plurality of optical fibers is used . Before Symbol transmitting diaphragm is an ultrasonic inspection apparatus according to claim 1, characterized in that it is formed of titanium. Before Symbol transmitting diaphragm is an ultrasonic inspection apparatus according to claim 1, characterized in that it is formed of aluminum. Before SL laser incident side of the transmitting diaphragm is an ultrasonic inspection apparatus according to claim 1, characterized in that it is restrained by the optical member. Before SL to the laser incident side surface of the transmitting diaphragm, ultrasonic inspection apparatus according to claim 1, jelly-like viscous material is characterized in that it is coated. A laser device that emits a laser beam with adjusted output; and
An ultrasonic transmitter having a transmission diaphragm that is irradiated with laser light emitted by the laser device and generates ultrasonic waves;
A beam diameter adjusting means for adjusting a beam diameter of the laser beam applied to the transmission diaphragm;
Each of the laser devices includes a plurality of optical fibers that emit the laser light and have different diameters.
The beam diameter adjusting means is for selecting which of the plurality of optical fibers is used,
Adjusting the beam diameter by the beam diameter adjusting means;
From the transmission diaphragm, the type of inspection object, the intensity of the ultrasonic wave corresponding to the inspection type is generated,
An ultrasonic inspection method characterized in that an inspection is performed by irradiating a subject with this ultrasonic wave. A nondestructive inspection method for a nuclear power plant, comprising performing a nondestructive inspection of the nuclear power plant using the ultrasonic inspection apparatus according to any one of claims 1 to 5 .

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